Handheld generator

ABSTRACT

The invention concerns a handheld power generator for generating electrical power for a consumer device, the generator comprising a main casing housing an input gear for driving an alternator via at least one intermediate gear so as to provide a step-up drive ratio in the range of 10:50; the input gear, the or each intermediate gear, and the rotor of the alternator all having their rotational axes perpendicular to the base of the main casing so that the gears and rotor rotate parallel to the plane of the base; a rectifier circuit for rectifying the alternator output; means for mounting a storage device for storing the output of the alternator, a control circuit for modifying the rectifier output to a voltage/current appropriate for the consumer device, and wherein the input gear is connected to a drive member rotatable by manual action to rotate the input gear in turn, the axis of the drive member being parallel to the respective axes of the input gear, the or each intermediate gear and the rotor with all the axes lying in a single straight line.

[0001] The present invention is concerned with devices by means of whichelectrical energy can be generated manually. Such devices are already inuse in radios but can also find application in cellphones, cordlesstelephones, two-way radios, PDA's, palm top devices, notebook computers,laptop computers, navigation devices such as GPS receivers, radios,torches, small lanterns, cassette players, CD players, MP3 devices,electronic game devices, fully or partially electrically powered modelssuch as aircraft and cars, emergency equipment such as locator beaconsor communication devices, and any other equipment normally usingelectrical power from batteries.

[0002] Such devices can be used to charge the batteries of electronicequipment and also can enable equipment to be used without dedicatedbatteries. Accordingly a device according to the present invention canbe used in a number of ways: firstly, as a replacement for a consumer'sstandard battery or batteries by using an external power plug on theconsumer's device. Secondly, as a replacement for the consumer'sstandard battery or batteries in which case the device according to thepresent invention could be a clip-on device. Thirdly, to charge thebattery or batteries of the consumer's equipment through the consumer'scharging plug or through the consumer's external power plug if theconsumer allows this. Fourthly, to supplement the consumer's batteryeither through the consumer's charging plug or through the consumer'sexternal power plug.

[0003] In accordance with the present invention there is provided ahandheld power generator for generating electrical power for a consumerdevice, the generator comprising a main casing housing an input gear fordriving an alternator via at least one intermediate gear so as toprovide a step-up drive ratio in the range of 10:50;

[0004] the input gear, the or each intermediate gear, and the rotor ofthe alternator all having their rotational axes perpendicular to thebase of the main casing so that the gears and rotor rotate parallel tothe plane of the base;

[0005] a rectifier circuit for rectifying the alternator output;

[0006] means for mounting a storage device for storing the output of therectifier circuit;

[0007] a control circuit for modifying the rectifier output to avoltage/current appropriate for the consumer device, and wherein theinput gear is connected to a drive member rotatable by manual action torotate the input gear in turn, the axis of the drive member beingparallel to the respective axes of the input gear, the or eachintermediate gear and the rotor with all the axes lying in a singlestraight line.

[0008] In order that the present invention may be more readilyunderstood, embodiments thereof will now be described by way of exampleand with reference to the accompanying drawings.

[0009] In the accompanying drawings:

[0010]FIGS. 1 and 2 are perspective views of a standalone accessory inaccordance with a first embodiment of the invention and for providingelectric power to a consumer device;

[0011]FIG. 3 is an exploded perspective view of the accessory of FIGS. 1and 2;

[0012]FIG. 4 is a longitudinal section through the accessory of FIGS. 1and 2;

[0013]FIG. 5 is an exploded perspective view of the alternator of theaccessory of FIGS. 1 and 2;

[0014]FIG. 6 is a block diagram of a control circuit;

[0015]FIG. 7 shows three perspective views of a second embodiment of astand alone accessory;

[0016]FIG. 8 is an exploded perspective view of the embodiment of FIG.7;

[0017]FIG. 9 is a section through the embodiment of FIG. 7;

[0018]FIG. 10 is an exploded perspective view similar to FIGS. 3 and 8of a third embodiment of an accessory in accordance with the presentinvention and for use with a mobile telephone;

[0019]FIG. 11 is a section through the embodiment of FIG. 10;

[0020] FIGS. 12 is a perspective view of a standalone cell phone chargerand detachable unit in accordance with another embodiment of the presentinvention;

[0021]FIG. 13 is a longitudinal section through the charger of FIGS. 1;

[0022]FIG. 14 is an exploded perspective view of part of the charger ofFIG. 12;

[0023]FIGS. 15A and 15B are a block diagram of a rectification andeffort indication power control circuit either of which can be housed inthe main body of the phone charger;

[0024]FIG. 16 is a block diagram of a control circuit housed in thedetachable unit, which will hereinafter be referred to in the specificdescription as a pod.

[0025]FIGS. 17 and 18 are perspective views of a flashlight inaccordance with another embodiment of the present invention;

[0026]FIGS. 19A, B, C and D are exploded perspective views of theflashlight of FIGS. 17 and 18;

[0027]FIG. 20 is a diagram of a power control circuit used in theflashlight; and

[0028]FIG. 21 is a perspective view of a novel stator which can be usedin all of the embodiments of the invention.;

[0029] FIGS. 22 to 24 are block diagrams of examples of output circuitsfor specific mobile phones.

[0030] Turning now to FIG. 1 of the accompanying drawings, this shows astandalone accessory having an external casing 1 carrying a foldingcrank arm 2. The crank arm 2 has a free end indicated at 3 and its otherend is pivotally connected at 4 to a crank 5. As can be seen from FIG. 2the pivot 4 enables the crank arm to be pivoted through substantially180° and has mounted on its free end a small rubberised handle 7. Whenthe crank arm is stowed in its inoperative position the small rubberisedhandle sits in a socket 8. The main casing 1 is configured so that itcan easily be held in one hand by a user so that the crank mechanism canbe operated by the user's other hand. In particular the outer casing isprovided with two chamfered portions 9 and 10 suitably dimensioned sothat they can be easily gripped by the fingers of a user.

[0031] For ease of assembly the casing 1 is manufactured in two partsnamely a top casing 11 and a bottom casing 12. The two casing halves areconnected by bolts (not shown) passing through cylindrical protrusions13 and 14 which also act to locate the top casing with respect to thelower casing when they are assembled together.

[0032] The length of the crank arm is designed to optimise power inputfor a particular input speed and the crank 5 itself is mounted on a lowfriction bearing.

[0033] As can be seen from FIGS. 3 and 4 the crank arm 2 is connecteddirectly to an input gear 15 which transfers the relatively low speedrotation from the crank mechanism to an intermediate gear 16. The inputgear 15 has straight cut teeth for high efficiency and as it transfershigh torque it also has wide tooth faces.

[0034] The intermediate gear 16 receives motion from the input gear viaa small diameter gear wheel 16′ and transfers motion from the input gear15 to an alternator assembly generally indicated at 17 via a largediameter gear 16″ which meshes with a small diameter gear 17′ of thealternator assembly. Thus the intermediate gear transfers motion fromthe input gear to the alternator assembly and at the same time increasesthe relatively low speed input from the input gear 15 to a high speedoutput suitable for the alternator. A suitable gearing ratio for thistransference is for one rotation of the input gear 15 causes between 10and 50 rotations of the alternator assembly 17. The choice of the gearratio is a matter of some importance. The ideal is to have a relativelow manual input rpm with high efficiency output from the alternator. Atypical input (crank) rpm which can be easily achieved by a user isbetween 100 and 140 rpm. If high power is requested from a small packagethen a higher gear ratio would be needed. However this can causeproblems because of a high initial torque requirement. In the presentembodiment the ratio is 24.

[0035] The alternator is shown in exploded form in FIG. 5 and analternator stator 18 carrying on its radial arms copper windings whichare not shown and an alternator rotor 20 in which are mounted magnetsegments 19 which provide the rotor poles. The alternator uses a threephase stator winding with nine stator teeth and twelve rotor polesmaking in total six pole pairs. It is of course possible that more thanthree phases may be used. The alternator rotor 20 is in the form of aflattened cup with a boss. The gear 17′ is mounted on this boss.

[0036] The magnets used in the alternator 17 are a high grade ofneodium-iron-boron (NFeB, or NiB) sintered rare earth magnets. Thealternator has a relatively high initial cogging torque, which ismultiplied backwards by the transmission ratio, so that an unacceptablyhigh starting torque can result. In order to reduce the effect of thiscogging torque the faces of the stator teeth are skewed about thealternator axis the stator pack in this embodiment are skewed about thealternator axis. It is possible for the laminations to be identical witheach lamination angularly skewed with respect to its neighbouringlaminations in order to achieve the necessary skewed effect. It is,however, preferred for the laminations to differ. This is described ingreater detail with respect to FIG. 21. The skewing of the laminationshas the secondary effect of smoothing the torque input and giving quietoperation even during high power generation. The alternator rotor 20 ismounted in a sintered brass bush impregnated with very low frictionlubricant.

[0037] The stator pack 18 is made up of a number of laminations of thinsteel so as to reduce eddy currents and their associated losses. Becauseof this high field strength it is essential to ensure the accuratelocation of the alternator rotor. Thus the alternator rotor 20 islocated axially only by the magnetic field associated with the magneticcircuit formed by the alternator stator, alternator rotor and the magnetsegments. Thus it is not fixed with regard to movement along the axis ofits rotation. This ensures that there is no axial bearing loss andlocates the alternator rotor automatically in the optimum position formaximum flux density in the stator teeth. The stator axial locating faceis machined with the rotor bearing housing in the same operation inorder to ensure that the stator and the rotor are properly aligned toavoid out of plane magnetic forces which would increase friction bearingand reduce flux density.

[0038] The output of the alternator 17 is taken to a rectificationmodule 21 which houses a three phase rectifier which converts the threephase alternating current power output from the alternator to directcurrent. If the device is intended to output a high voltage surfacemounted Schottky barrier diodes are used for passive rectification. Forlow voltage devices an active rectification system is used to minimiserectification losses and maximise efficiency. Both these rectificationcircuits are completely conventional.

[0039]FIG. 6 of the accompanying drawings is a block diagram indicatingthe layout of the alternator and subsequent circuitry. Thus the outputof the rectification module 21 is supplied to a storage device, thisstorage device accepts energy in an electric format that is optimizedfor the highest power density and efficiency from the alternator and isspecified in such a way as to accept high energy power density andefficiency from the alternator and is specified in such a way as toaccept high energy content in a short period of time. Typical examplesof such energy storage devices are secondary cells such as NickelCadmium rechargeable, Nickel Metal Hydride rechargeable, Lithium Ionrechargeable and Lithium Polymer rechargeable batteries as well ascapacitors of large capacity. The storage device subsequently deliversthe electricity to an output jack 23 that plugs into the consumer devicevia. power control circuitry 22. The output from the control block 22is, amongst other factors, essential to perform conversion from the dcconstant voltage from the storage device to the power format required bythe consumer device. Thus the output from the power control block 22 maytake a range of formats which may include pulsed voltage, currentlimited constant voltage, sinusoidal voltage and current/constantvoltage as required.

[0040] It will be appreciated when the generator is used for mobilephones, for example, that each mobile phone company produces mobilephones which have different protocols with regard to the way in whichthe phones will accept power at the start of and during their operation.The output of the power control block is supplied to an output jack 23by means of which the device can be connected to a consumer deviceeither directly or via an appropriate cable.

[0041] Where the battery module contains a plurality of batteries, thepower control module can be arranged so that when the batteries arebeing charged they are charged in series so as to allow a high inputvoltage and thus more efficient operation of the alternator.Alternatively, when the output of the battery is being used to drive aconsumer device the batteries are discharged in parallel at cell voltagewhich is likely to be a voltage both more suited to the power controlmodule and the consumer device.

[0042] Also shown in FIG. 6 is a mains ac input 25 by means of which thebattery or batteries can be charged via a charge control module 26. Insome cases the ac input may be a dc input. Finally, FIG. 6 shows indiagrammatic form a solar panel 27 which can also be used to provide asteady charge to the battery or batteries in the battery module. As canbe seen this power input does not act via the power control module 22.

[0043] Turning now to FIGS. 7, 8 and 9 of the accompanying drawings itwill be seen that these show a hand-held generator very similar in manyaspects to the first embodiment.

[0044] This second embodiment is particularly concerned with dealingwith the conflicting requirements of providing a portable, hand-heldgenerator which is both compact and yet efficient. As the generatorlargely uses a manual input it will be appreciated that there is a linkbetween efficiency and ease of use and the length of the crank arm bymeans of which a user imparts drive to the generator.

[0045] In the first embodiment the length of the crank arm is limited bythe length of the casing as the handle on the end of the arm has to bestored in a recess in the casing. Thus it is difficult to provide both acrank arm of a length which is ergonomically efficient and a devicehaving a short overall length. This is the problem addressed in thesecond embodiment.

[0046] In FIGS. 7, 8 and 9 integers which are common to the firstembodiment have been given the same reference numerals.

[0047] Referring now to FIG. 7 the first of the views shows the crankarm 2 in its stored position. The rubberised handle 7 is larger than thehandle 7 of the first embodiment and accordingly is also moreergonomically efficient. This increase in size of handle 7 is achievedby providing the end of the main casing 1 with an open-ended recess 8into which the handle 7 is a clip fit. It will also be seen that theupper surface of crank arm 2 is provided at 2′ with a series of ridges.These are intended to provide purchase for a user's fingers. Finally thecrank arm 2 is linked to its pivotal connection to the crank 5 via asliding coupling. This coupling will be described in greater detailhereinafter but by means of the sliding coupling and the ridges 2′ thehandle 7 can be unclipped from the recess 8 and moved in the directionof arrow A. The crank arm is then pivoted as shown by arrow B into itsoperative position in which the ratio of its operative length to thelength of casing 1 is greater than the corresponding ratio of the firstembodiment.

[0048] Referring to FIGS. 8 and 9 of the accompanying drawings it willbe seen that the arrangement of input gear 15, drive gears 16 andalternator 17 are identical to he first embodiment. Additionally thecontrol circuitry of this embodiment is the same as that of the firstembodiment as is the battery. Thus these integers together with thebattery will not be described further. However in the second embodimentthe pivotal coupling is provided by a cross rod 4′ mounted on the crank5 and located in a longitudinal slot in the end of the crank arm 2. Inthe stored position of the crank arm as shown in FIG. 9 the pivot armabuts the left hand edge of the slot whilst once the crank arm is movedin the direction of arrow A in FIG. 7 it will abut the right hand edgeof the slot thus providing a useful extension of the crank arm's length.

[0049] Turning now to FIGS. 10 and 11 of the accompanying drawings itwill be seen that these Figures discloses a third embodiment of thepresent invention.

[0050] In particular the embodiment of FIGS. 10 and 11 is a clip-onaccessory which can be clipped on to a device such as a cellphone so aseither to replace the device's normal battery power supply or in fact asto act as the main supply of the consumer device to which it isattached.

[0051] Referring now to FIG. 10 of the accompanying drawings this showsthe third embodiment with its top casing 30 separated from the main body31 of the device with the operative portion of the device clipped intoplace on a cellular phone generally indicated at 32.

[0052] As with the previous embodiment the device includes an input gear15 meshing with an intermediate gear 16 in turn driving an alternatorassembly 17 via a gear 17′. The construction of the alternator assembly17 and the associated drive gearing is very similar to that disclosed inthe first embodiment so that similar reference numerals are used.Additionally the design of the alternator rotor, magnets and statorwinding are the same as that of the previous embodiments except that thestator rotor is inverted. However, in this embodiment the method bywhich a user rotates the input gear 15 is different in that it comprisesa pull-cord 33 wound around a bobbin 34 provided with a pair of constanttorque springs 35 which act to return the cord into the wound conditionafter it has been pulled by a user. Only one spring 35 is shown. The twosprings are mounted on respective spring posts and a spring-lockingcollar. Thus the bobbin acts to translate the linear motion of the cordinto rotational motion and to house the pull-cord 33. The cord 33 whenwound up is housed between spaced circular flanges 36. The bobbin ismounted on a one-way clutch bearing 37 which transmits its motion whenrotated by the pull cord to the input gear 15. Preferably the cord isfurnished at its free end with a loop which fits around a user's wrist.The input gear 15 meshes with an intermediate gear 16 which in turndrives an alternator gear 17′ as in the previous embodiments. In thisembodiment the gear ratio between the drive bobbin and the alternatorrotor is preferably between 9 and 17. The detailed construction of therotor and stator of the alternator 17 is identical to that of thealternator of the first embodiment and so will not be described again.

[0053] The clip-on accessory is provided with a base plate 38dimensioned to fit the mounting area on the rear face 39 of thecellphone 32 which would normally receive the cellphone's battery pack.Immediately above this base plate the clip-on accessory houses a batteryor batteries 41 which can be of exactly the same type as the batteriesdescribed in the first embodiment.

[0054] Additionally as with the previous embodiment the clip-on deviceis provided with a power management module 21 which is similar to thatdisclosed in the first embodiment but as the clip-on device is designedfor a specific phone unit once again the operation of the powermanagement module will be dependent on the nature of power required bythe cellphone so that in many instances a simpler power management unitcan be employed. In particular the Clip-on unit does not need to followthe charging protocols of the previous embodiments as there is directaccess to the phone's own battery.

[0055] Turning now to FIGS. 12 of the accompanying drawings this shows aperspective view of a hand-held generator particularly designed for cellphone.

[0056] Thus FIG. 12 shows a cell phone charger having an external casing100 carrying a folding crank arm 102. The crank arm 102 has a free endindicated at 103 and its other end is pivotally connected at 104 to acrank 105. The pivot 104 enables the crank arm to be pivoted throughsubstantially 180° and the arm has mounted on its free end a handle 106which can pivot about a pivot post 107. When the crank arm is stowed inits inoperative position the handle sits in a socket 108. As in theprevious embodiments the main casing 100 is configured so that it caneasily be held in one hand by a user so that the crank mechanism can beoperated by the user's other hand.

[0057] For ease of assembly the main casing 100 is manufactured in twoparts 109 and 110.

[0058] The length of the crank arm is designed to optimise power inputfor a particular input speed and the crank 105 itself is mounted on alow friction bearing.

[0059] The generator mechanism to which the crank 105 is attached isidentical to that already described and so will not be described again.

[0060] As can be seen from FIG. 12 the two casing parts 109 and 110 whenbolted together sandwich a central substantially planar body 121 whichcarries a circuit board 122 for regulating the output of the alternatorand having four connection pads. These pads are shown in FIG. 15 whichshows circuit board 122 in greater detail. The main unit also houses aLithium-ion battery 124. This battery can be charged either by thealternator or by the charger unit normally supplied with every cellphone, the power from the charger unit being supplied, as will bedescribed hereinafter, via the detachable pod. As can be seen from FIGS.13 the main generator unit has an LED 125 for indicating usable outputfrom the alternator. The other main component of the device as shown inFIGS. 12 and 13 is a detachable pod generally indicated at 126. This podis also made from two molded halves which are shown in FIG. 14 at 127and 128 and which are secured together so as to locate a central plate129 carrying a circuit board 130 which has four copper connection points131 for connection to the corresponding output pads 123 of the circuitboard 122 of the main generator unit. The pod 126 also carries an outputcable 132 the free end of which carries a connector appropriate to theparticular cell phone with which the entire assembly is to be used. Thecircuitry in circuit board 129 will be described in greater detailhereinafter but amongst other functions ensures that the output of themain unit takes a format appropriate to the particular cell phone withwhich this generator is to be used. As already stated it must beappreciated that virtually every cell phone manufacturer has differentstandards by means of which their particular cell phones will onlyaccept a particular format of charging current and voltage. Thesestandards are proprietorial to the individual manufacturers and are setby appropriate, but entirely conventional circuits. The main casingcarries an LED 125 which be used. Additional pod 126 carries an LED 133which is used as an indication to a user when the battery in the mainunit is being charged by a standard mains powered charger via the pod.

[0061] Turning now to FIG. 15 of the accompanying drawings this showsthe circuit of the circuit board 122. In this circuit the output of thealternator is connected to contact pads 140, 141 and 142 and isrectified by diodes 143, 144, 145, 146, 147 and 148 so as to charge thebattery 124 which in operation is mounted between contact pads 149 and150.

[0062] In operation current flows through diodes 146, 147 and 148 to pad149 and via the battery 124 to pad 150 and back to diodes 143, 144 and145.

[0063] The circuit of FIG. 15A also includes an effort indicator circuitto show that meaningful output is being created by the alternator. Inthe effort indicator circuit alternator output is taken from pad 140 viahalfwave rectifier diode 151 and is smoothed by capacitor 152. A highprecision reference circuit 155 will try to divert this current viadiode 151, capacitor 152, its “K” terminal and terminal “A” to groundwhen the voltage across capacitor 152 exceeds a pre-set voltage. Thispre-set voltage is set by the ratio of resistors 153 and 154, thejunction of which is connected to the reference input of referencecircuit 155. Current will also be diverted via the emitter and base oftransistor 156 and resistor 158 to reference circuit 155. Thustransistor 156 will switch on. Current will then flow from the emitterand collector of transistor 156, resistor 160, pad 162, LED 125, pad163, to ground and the LED 125 will illuminate to show optimum input.The circuit of FIG. 15 can be coupled to the circuit shown in FIG. 16via pads 76, 77, 78 and 79. Pads 80 are in operation connected to earth.

[0064] Sensing effort using the voltage generated presents a problem inthat there can be substantial voltage changes over a relatively smallrange of input RPM. It will be appreciated that it is also possible tomeasure input effort by monitoring the generated current and this iswhat is done in FIG. 15B. The components of FIG. 15B are allconventional.

[0065] Turning now to FIG. 16 of the accompanying drawings, this is acircuit diagram of the circuitry carried by the detachable pod.

[0066] As already mentioned it is possible to charge the battery fromthe original cell phone charger. This can be done via a standard socket270 to which the output of the original cell phone charger is connected.When the battery 124 is charged from the original cell phone charger thelatter is connected to socket 270 and the current flows a path from pin14 of socket 270 via diode 271, resistors 272 and 273, the source anddrain of transistor 274, pad 275, pads 76 and 77 of the circuit of FIG.6, pad 149, the battery 124, pad 150, earth pads 80, and finally pad 244to pin 10 of connector 270. The transistor 274 is controlled by pin 3 ofintegrated control circuit 275.

[0067] Current also flows from diode 271 to pad 283 and then to pads 78and 79 of the FIG. 15 circuit. From there the current flows via resistor161, pad 162, LED 125, pad 163 to earth. The LED 125 glows to show thatthe unit is under charge conditions. The diode 271 is used for polarityprotection and resistors 272 and 273 set the charging current. Theintegrated circuit 175 also monitors the battery voltage at pin 5 toensure that when the battery is fully charged, the current drops to avery low value.

[0068] The timer and regulator operation of the circuit on the pod is asfollows. The switch 286 starts the charging cycle by turning transistor244 on. In the present embodiment transistor 244 is a MOSFET transistor.Power is accordingly supplied to pin 16 of integrated circuit 249 andcapacitor 246 and resistor 247 resets the timer by giving a high pulseto circuit 249. Pin 2 of circuit 249 goes low and holds the transistor244 on. Current also flows through LED 133 and resistor 254 to show “anon” condition.

[0069] Power is also applied to the dc-dc switch mode converter 277which provides a higher output voltage with a very rapid switchingaction. When the internal switch inside converter 277 is on currentflows from pad 240, outputs 5 and 6 of circuit 244, resistors 273 and274, coil 275, output 1 of integrated circuit 277, output 2 of the samecircuit to pad 284. When the internal switch turns off the magneticfield in coil 275 decreases causing a voltage across itself. The supplyvoltage is therefore in series with this voltage. The current flows frompad 240, transistor 244, resistors 373 and 374, coil 275, diode 278, pad283, via the cell phone back to pad 284. The current also chargescapacitor 281. The internal switch of converter 277 turns on again andthe cycle is repeated. This happens thousands of times per second. Sincethe voltage across the coil 275 is in series with the supply voltage,the output voltage is higher than the battery voltage.

[0070] The output voltage at pad 283 is fed back to converter 277 toinput 5 of the latter via resistors 270, 271 and 272 and the output willchange so that the voltage at 5 of converter 277 is always 1.25V.Therefore the ratio of resistors 270/271 and 272 effectively sets theoutput voltage if the effect of resistor 266 is ignored.

[0071] The voltage back from the cell phone being charged which appearsat pad 282 modifies the output voltage as follows. The following tablesets out three cases. Before discussing each of the cases individuallythe voltage at the junction of resistor 269 and resistor 164 is heldconstant at 2.5V by shunt regulator 268. A current flows via resistor269, resistor 257, transistor 258 and resistor 261 to earth. Since thevoltage at the top of resistor 257 is constant, then this current isalso constant. Since the voltage at the base of transistor 258 isconstant, the voltage at the base of transistor 262 is also constant andtherefore the current flow via resistor 264, transistor 262, emitter tocollector is exactly the same as that through resistor 257. This currentthen splits through transistor 263, resistor 267 to earth or resistor261 to pin 5 of converter 277. The voltage at pad 282 determines theproportion of this current split.

[0072] The three cases set out in the table will now be discussed ingreater detail.

[0073] Case 1—The voltage at pad 282 is too low to turn transistor 263on. All the current from the collector of one of transistor 262 flowthrough resistor 266 via resistor 272 to earth. The output voltage isthus fixed at 4.4V.

[0074] Case 2—The voltage at pad 282 starts to turn on transistor 263.This reduces the current through the resistor 266. The voltage at pin 5of converter 277 will therefore try to decrease. The output voltage atpad 283 will increase to maintain pin 5 of converter 277 at 1.25V.

[0075] Case 3—The voltage at pad 282 has turned transistor 263 fully on.The current through the transistor is at a maximum value and cannotincrease further. The current through resistor 266 cannot decreasefurther and therefore it has no effect on the output voltage.

[0076] At the end of the timing cycle pin 2 of circuit 249 goes high andstops the timer by putting a high voltage via the diode 250 to pin 10.It also removes drive from transistor 244 and thereby switches it off.The voltage on the output of transistor 244 goes to zero.

[0077] In the present embodiment the voltage across resistors 373 and374 is detected by converter 277 and used as a measure of the currentflowing to the output. If there is too much current flowing thenconverter 277 will “current limit” to prevent excessive heat and/or thecircuit from being operated outside its parameters.

[0078] Resistors 257 and 264 are fitted to minimise differences betweenthe emitter base voltages of transistors 258 and 262 having an effect onthe accuracy of the “current mirror”. Capacitors 280 and 281 are used tosmooth the dc output.

[0079] Turning now to FIG. 17 of the accompanying drawings, this shows atorch having an external casing 201 carrying a folding crank arm 202.The crank arm 202 has a free end indicated at 203 and its other end ispivotally connected at 404 to a crank 405. As can be seen from FIG. 18the pivot 404 enables the crank arm to be pivoted through substantially180° and has mounted on its free end a small rubberised handle 406. Whenthe crank arm is stowed in its inoperative position the handle sits in asocket 407. The main casing 401 is configured so that it can easily beheld in one hand by a user so that the crank mechanism can be operatedby the user's other hand.

[0080] For ease of assembly the casing 401 is manufactured in two partsnamely a top casing 408 and bottom casing 409. The two casing halves areconnected by bolts (not shown) passing through cylindrical protrusions410 and 411 which also act to locate the top casing with respect to thelower casing when they are assembled together.

[0081] As in the previous embodiments the length of the crank arm isdesigned to optimise power input for a particular input speed and thecrank 405 itself is mounted on a low friction bearing.

[0082] The crank arm 402 is connected directly to an input gear 15 whichtransfers the relatively low speed rotation from the crank mechanism toan intermediate gear 16 and thence to an alternator 20. The geararrangement and the structure of the alternator are similar to that ofthe other embodiment and so will not be described again.

[0083] As can be seen from FIG. 19 the two casing halves 408 and 409 arebolted together on either side of a central, substantially planar, unit421. This unit 421 carries a circuit board 422 and also has mounting 423for one or more batteries which are preferably of the lithium ion orlithium polymer type. The upper casing half 408 carries a switch 424 bymeans of which a user can turn the flashlight on and select either highor low output filaments from a two-filament bulb (not shown) mounted ina standard reflective casing 425. The flashlight also has a socket 426from which the battery/batteries can be charged from an external powersupply and a light, preferably an LED 427, the purpose of which will bedescribed hereinafter.

[0084] The operation of the circuitry of the circuit board 422 will nowbe described in relation to FIG. 20 of the accompanying drawings.

[0085] The three-phase output of the alternator is connected via pads428, 429, 430 to a rectifier module consisting of diodes 431, 432, 433,434, 435 and 436 so as to charge a battery 437.

[0086] An “effort indicator” circuit comprises a programmable referencedevice 438 and a transistor 439 with associated resistors 440, 441, 442,443 and 444 which monitors the alternator output and lights up the LED427 when there is meaningful output from the alternator.

[0087] The output of the alternator can also be used to drive thefilaments of the two-filament bulb indicated at 445 and a low drop outregulator circuit is used to limit the voltage which can be supplied tothe bulb 445 from the alternator to 3.3. volts. Naturally other voltagesmight be used for different types of bulbs.

[0088] The low drop out regulator circuit comprises a comparator 446 anda pair of transistors 447, 448. The reference voltage used by comparator446 can be trimmed using resistors 480 and 481 to take componenttolerances into account.

[0089] Power to the bulb 445 is controlled by the switch 424 which is athree-position switch shown in the “OFF” state. One pair of terminalsconnect to the high power filament of the bulb 445 when bright light isrequired and the other pair connects power to the low power filamentwhen power conservation is required.

[0090] In this embodiment the battery 437 can be charged from anexternal source via a socket 456, via a diode 457 and resistors 458 and459.

[0091] The diode 457 is used for polarity protection and the resistors458 and 459 to set the charging current drawn from the external adaptor.Resistors 458 and 459 also limit the charging current if the bulb is onand the battery is flat.

[0092] When the battery 437 is being charged by the alternator currentflows via diodes 432, 434 and 436 and contact pad 470 to the battery 437and then back via a contact pad 476 and a resistor 463 to diodes 431,433 and 435.

[0093] As mentioned the circuit includes an effort indicator to show auser that the alternator is providing a meaningful output. In the effortindicator circuit power from the alternator is taken via pad 428 and ahalf-wave rectifier diode 464. This power is smoothed by a capacitor465.

[0094] The programmable reference circuit 238 will try to divert thecurrent from diode 464, resistor 442, and its terminal to ground whenthe voltage across capacitor 65 exceeds a preset voltage. This presetvoltage is set by the ratio between resistors 440 and 441, the junctionof which is connected to the reference input of reference device 438.Current will also be diverted via the emitter and base of transistor439, resistor 443 to reference circuit 438. Thus transistor 439 willswitch on so that current flows from the emitter of transistor 39, itscollector, pad 460, LED 427, pad 461 and resistor 444 to ground so thatthe LED 427 will illuminate to show optimum input. The final maincircuit is the main regulator circuit for the bulb. This circuitincludes operational amplifier 446 which compares the voltage of theoutput across capacitor 466 via resistors 467 and 468 with a referencevoltage at pad 469. The output of the operational amplifier 446 drivestransistor 447 via transistor 448 so that the output voltage is keptconstant.

[0095] When the torch is switched on then current flows from battery237, positive pad 470, pad 471, switch 424, pad 472 through the emitterand collector of transistor 447, pad 473, pad 474, bulb 445, pad 475,and pad 476 to the negative terminal of the battery 437.

[0096] Current also flows via resistor 449 and programmable precisionreference circuit 477 to ground to provide a reference voltage at pins 1and 3 of the precision reference circuit 477. This voltage is divided inhalf by resistors 428 and 479 and this voltage is applied via pad 469 tothe minus input of operational amplifier 446. To allow for tolerances inthe reference voltage, a facility is provided to adjust the voltageslightly up or down by means of strapping pad 469 to either resistor 480or resistor 481 via respective pads 482,483. Stability for the precisionreference circuit 477 is provided by means of capacitor 484.

[0097] If the output across capacitor 466 is lower than desired then thevoltage at the junction of resistors 467 and 468 will also be lower.Thus the voltage at the plus input of the operational amplifier 446 willbe lower than that at its minus input. The output voltage of theoperational amplifier 446 will therefore decrease. Current flow willincrease from emitter and base of transistor 447, emitter and base oftransistor 48 to the output of the operational amplifier 446.

[0098] Current flow will consequently increase from the emitter and baseof transistor 447, emitter and collector of transistor 448 via resistor52 to ground. This increase in current through emitter and base oftransistor 447 will therefore turn it on to a greater degree. Thevoltage across capacitor 466 will increase until the voltage on bothinputs of the operational amplifier 446 are the same.

[0099] If the output across capacitor 466 is higher than desired, thenthe voltage at the junction of resistors 467 and 468 will also behigher. Thus the voltage at the plus input of the operational amplifier446 will be higher than that at its minus input. The output voltage ofthe operational amplifier 446 will therefore increase. Current flow willtherefore decrease from the emitter and base of transistor 447, emitterand base of transistor 448 and resistor 451 to the output of theoperational amplifier 446. Current flow will consequently decrease fromthe emitter and base of transistor 447, emitter and collector oftransistor 448 and resistor 452 to ground. This decrease in currentthrough the emitter and base of transistor 447 will therefore turn it onto a lesser degree. The voltage across capacitor 466 will decrease untilthe voltage on both inputs of the operational amplifier 446 are thesame. Resistor 450 is present in order to switch transistor 447 off ifthe output of operational amplifier 446 is high.

[0100] From the above it will be appreciated that switch 24 can connectthe battery from the regulator circuit and selects either normal andhigh filaments of the lamp in accordance with whether pads 471/472 and473/474 are contacted or pads 471/485 and 473/486.

[0101] From the above description it will be seen that a simple circuitis provided which enables a carefully regulated voltage to be suppliedto the bulb either from the alternator if the battery is flat or fromthe battery. Additionally the battery can be charged from the alternatorinput or from an external power supply. The resulting flashlight is bothcompact, easy to handle and highly efficient.

[0102] Referring now to FIG. 21 it will be appreciated that a discussionhas already been given with regard to the importance of reducing thecogging effect when the generator is initially started. In order toreduce the cogging effect both the stator laminations and the permanentmagnets were skewed. It has now been found that the performance of thestator can be improved by not using identical laminations each of whichis angularly displaced with respect to its neighbour. In the FIG. 21embodiment the requisite skewing effect of the stator teeth is providedby varying each lamination and specifically by varying the teeth of thelaminations which are shown at 501. It will be seen that each tooth 501extends on either side of its stator arm with the anti-clockwiseextension of the teeth of the uppermost lamination being substantiallylonger than the clockwise hand extension. The skewed effect is obtainedby progressively reducing the anti-clockwise extensions andprogressively increasing the clockwise extensions. This arrangementenables the copper windings around the arms 500 of the stator to be moreeffective as the cross-sections of the actual arms 502 are not skewed sothat it is no longer necessary to skew the alternator rotor magnets. Inthe FIG. 21 variant there is a central lamination with three pairs ofdifferent laminations, the laminations above the control laminationbeing inverted with respect to the laminations below the centrallamination.

[0103] FIGS. 22 to 24 are all examples of specific control circuitsdesigned to be associated with particular mobile phones. All these fourcircuits had centrally the same basic components which comprise a seriesof inputs indicated at 400 for receiving charge either from the batteryin the main housing or from the standard charger provided with themobile phone. Section 401 is used to ensure that if there is an error inthe voltage supplied at the input side or the phone attempts to draw toomuch power through the circuit that the phone and/or the charger unit issuitably protected. Section 402 actually deals with the over drive tripand section 403 tracks phone power usage and provides appropriatecompensation. Section 404 actually converts the supplied voltage intothe appropriate format for the phone and sections 405 and 406 arerespectively a power stage and an external current/limit, output enablecircuit. The embodiment of FIG. 23 is a simplified version of theembodiment of FIG. 22 and accordingly only has the sections 400, 401,402 and 405. The circuit of FIGS. 24 has only minor alterations withregard to the circuit shown in Figure 22. All of the components of thesecircuits are conventional.

1. A handheld power generator for generating electrical power for aconsumer device, the generator comprising a main casing housing an inputgear for driving an alternator via at least one intermediate gear so asto provide a step-up drive ratio in the range of 10:50; the input gear,the or each intermediate gear, and the rotor of the alternator allhaving their rotational axes perpendicular to the base of the maincasing so that the gears and rotor rotate parallel to the plane of thebase; a rectifier circuit for rectifying the alternator output; meansfor mounting a storage device for storing the output of the alternator;a control circuit for modifying the rectifier output to avoltage/current appropriate for the consumer device, and wherein theinput gear is connected to a drive member rotatable by manual action torotate the input gear in turn, the axis of the drive member beingparallel to the respective axes of the input gear, the or eachintermediate gear and the rotor with all the axes lying in a singlestraight line.
 2. A generator according to claim 1 wherein one end ofthe drive member is pivotally connected to one end of a crank arm whichis movable into an operative position from a stored position in which itlies parallel to the base of the casing which with its free end held ina recess in the other end of the casing, the longitudinal axis of thecrank arm in its stored position lying orthogonally across the axes ofrotation of the gears and the alternator.
 3. A generator according toclaim 2, wherein the crank arm is adapted to pivot through approximately180° from its stored position into its operative position, and thelength of the crank arm is variable so that its length is greater in theoperative position than in the stored position.
 4. A generator accordingto claim 3, wherein the crank arm has at its free end a handle extendingtransversely from crank arm, and wherein the main casing is providedwith a recess in which the handle fits only when the crank arm is in itsshortest state.
 5. A generator according to any preceding claim whereinsaid drive member is a bobbin coupled via a unidirectional clutch to theinput gear and having mounted thereon a pull-cord by means of which thebobbin can be rotated to impart drive to the input gear so as to drivethe alternator to generate current.
 6. A generator according to claim13, including a spring biasing the bobbin to the condition in which thedraw-cord is stored around the bobbin.
 7. A generator according to anyone of the preceding claims wherein the generator comprises analternator rotor housing an array of magnets and rotatable with respectto a stator, the stator being formed from a plurality of laminations. 8.A generator according to claim 7 wherein the stator teeth are skewedwith respect to the rotation axis of the alternator so as to reducecogging effects.
 9. A generator according to claim 8, wherein the statorlaminations each have a plurality of identical stator arms which arealigned with each other, the arms of each stator lamination carrying atooth portion transverse to the arm, the tooth portion of each statorlamination being different from to the tooth portions of the otherstator laminations so that the teeth of the stator formed by the toothportions are skewed but the stator arms are not.
 10. A generatoraccording to any of claims 7, 8 or 9, wherein the alternator rotor isaxially located only by the magnetic field associated with the magneticcircuit formed by the stator and the alternator magnets.
 11. A generatoraccording to any preceding claim and including a mounting for at leastone rechargeable battery.
 12. A generator according to claim 10, whereinthe alternator is adapted to charge the battery through the rectifier.13. A generator according to claim 11 or claim 12, including a socketwhereby the generator can be connected to another outlet so that eitherthe battery or a device can be charged via the generator.
 14. Agenerator according to any one of claims 11 to 13 and including at leastone solar panel for charging the battery.
 15. A generator according toany one of claims 1 to 10 and having a main body housing the drivemember and the alternator, the main body having an output socket forattachment to a detachable unit containing circuitry for adapting theoutput of the power generator to a particular model of cell phone.
 16. Agenerator according to claim 15 in combination with a detachable unit inthe form of a pod containing circuitry for adapting the output of thepower generator to a particular model of cell phone.
 17. A generatoraccording to claim 16, wherein the pod can be clipped into a monitoringrecess in the main body.
 18. A generator according to claim 15, 16 or 17and including means for mounting a battery which can be charged by thegenerator so that when charged the battery can provide power via thedetachable unit to a cell phone.
 19. A generator according to any one ofclaims 15 to 18 wherein the main body houses a light source and acircuit adapted to control the light source to show to a user thatmeaningful output is being generated by the alternator.
 20. A generatoraccording to claim 18 or claim 19 wherein the detachable unit has asocket adapted to co-operate with the output of a cell phone charger sothat a battery mounted in the main body can be charged via a cell phonecharger.
 21. A generator according to claim 20, wherein the detachableunit includes a light source for indicating that charging from anoutside source is being carried out.
 22. A generator according to anyone of claims 1 to 14 including means for mounting a bulb so that thegenerator/bulb combination can act as a flashlight and wherein thegenerator further comprises a battery mounting in which a battery orbatteries can be mounted so that when mounted the battery/batteries canpower a mounted bulb, and a switch means whereby the battery or thealternator can either power the bulb or the alternator charge thebattery.
 23. A generator according to claim 22 comprising switch meansfor switching power to the bulb mounting so that a mounted bulb canoperate in either a bright, high power consumption mode or a lessbright, lower power mode.
 24. A flashlight according to claim 22 orclaim 23 including a socket for receiving external power to charge saidbattery/batteries.
 25. A generator according to any one of claims 22 to24 including means for indicating to a user that the alternator isgenerating sufficient power.
 26. A generator according to any one ofclaims 22 to 25 and including a regulator circuit for regulating powersupplied to a mounted bulb.
 27. A generator according to any one ofclaims 22 to 26 wherein the flashlight has an outer casing of plasticsmaterial bolted around a substantially planar support carrying a circuitboard for controlling the output of the alternator.